1. Field of the Invention
This invention relates to a process and apparatus for continuously producing glycerol dichlorohydrin.
2. Description of the Prior Art
It is known that, when allyl chloride is caused to react with chlorine in the presence of water, glycerol dichlorohydrin comprising 1,3- and 1,2-isomers will be obtained in accord with the following equation: ##EQU1##
However, generally, in this and similar chlorohydrination systems, competing secondary reactions occur producing by-products such as 1,2,3-trichloropropane and tetrachloropropyl ether according to the following equations: ##EQU2## These reactions interfere with the production of glycerol dichlorohydrin, reducing the yield and the quality of the product.
It is known to effect chlorohyrination of allyl chloride continuously by introducing allyl chloride in the liquid state into a vertical reaction column or tower filled with chlorine water. This method produces considerable quantities of trichloropropane, and the reaction must be carried out using an element for effecting vigorous agitation or a dispersing pump to reduce the formation of by-product. However, even in such a system the level of by-product has been undesirably high, and the yield of glycerol dichlorohydrin has been industrially unacceptably low.
There is also known a process for continuously producing glycerol dichlorohydrin by introducing gaseous allyl chloride into an environment, such as a vertical reaction column, charged with chlorine water. In this case, also, the yield of glycerol dichlorohydrin has been industrially unacceptably low.
Furthermore, when operating these prior processes so as to favor the production of a product solution of glycerol dichlorohydrin of greater than 6% w/w concentration, the yield is further reduced.
Apparatus has been suggested comprising two paired vertical columns charged with aqueous media into which are dispersed respectively chlorine gas and an olefine such as ethylene. The resulting dispersions are cross-flowed to form the charged medium of the opposite column of the pair, hence to introduce chlorine directly into the charged ethylene and to introduce ethylene into the chlorine water. As it would cause the introduction of allyl chloride directly into chlorine water, this apparatus is not satisfactory for the production of glycerol dichlorohydrin by the process involving equation (I) above.